Cable insulating and testing system.



No. 882,141. I PATENTED MAR. 1'7, 1908.

. T. COPE.

GABLB INSULATING AND TESTING SYSTEM.

APPLICATION FILED JUNE 30. I906.

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WITNESSES.-

UNITED STATES PATENT o Fion TROY COPE, OF NEWWATERFORD, OHIO.

CABLE INSULATING AND TESTING SYSTEM.

Specification of Letters Patent.

Patented March 17,1908.

Application filed 1...... so, 1906. Serial No. 324,136.

specification My invention relates to cables for the conducting of electric currents and particularly to that class of electric cables used in telephone and telegraph systems which are provided with an external sheath or covering of lead 'or other metal, and which have between the several Wires comprising. the cable more or less, air space or voids due to the-loose wrapping of the insulation on said bundles of wires, and which are known generally in the art as drycore cables.

The objects of my invention are to main-- tain a high degree of insulation in the wires composing the cable and to provide a convenient and accurate means of detecting and locating leaks and breakdowns in the cable sheathin My device is designed for use with -a system of cables having metal or other sheathing impervious, in its normal state, to the passage of air and having air or' gas introduced through suitable inlets into said cable and filling the voids between the wires of the cable, the said air or other gas being at a higher pressure than the atmosphere surrounding the cable. 1

In practical telephone or telegraph dry core cable construction, at the joints in said cables Where the wires are spliced, the voids which would otherwise exist between the wires within the metal sheath are liable to, and actually do, become filled and clogged by the insulating compound which is applied in a liquid or plastic state, and whiohupon hardening, interrupts the continuity of the air passages. This defect I also aim to remedy by my invention as will be more particularly described hereinafter. a I

- In the accompan ing drawings which form part of this'speci cat1on:Figure 1 represents a diagrammatic view of a section of a cable system showing the means for introduci'ng the air pressure within the cables. Fig. 2 represents an indicating device for insertion at the by-passes in the cables. Fi 3 represents a cross section of a metal sheat ed cable to 'illustratethe voids therein.

Referring again to the drawings :1 1

are cables having the metal sheath 2 and ending at the terminal board 3.

with suitable'insulating compound as shown at 5 completely filling the spaces between the wires 66 and preventing escape of air The cross. section at the ends of the cables. of cable represented in Fig. 3 clearly shows the Wires 6 having loosely wrapped paper or other hygroscopic insulating material, the

The joints 44 adjacent to the terminal board are filled metal sheath 2 and the voids 7 between the I wires.

44* indicate splicing joints which ma occur in the length of the cables and whic may also represent a repaired breakdown occurring in the circuit and shows how the voids are filled with insulating compound 5, completely filling the voids at these points and interrupting the continuity of the said voids as passages for air along and within the cables.

Air or gas'under ressure contained in a suitable reservoir 8 aving a pressure gage 9 is introduced into the several cables by means of the tubes 1010, having cocks A 11-11. A regulating valve 12 reduces the air to the desired pressure which is indicated by the gage 13. Meters or other indicating devices 1414 are inserted in the lines 1010 to register the quantity of air passing into each cable and serve to immediately detect any leak in its cable when the quantity of air passing is above the normal.

In practice it is the custom in repairing breakdowns occurring in the cable, to insert Within the metallic sheath some'insulating compound in a liquid orplastic state at the defective point, which'surrounds the wires and fills the voids and interstices in the cable and which upon hardening interrupts; the continuity of the cable for t e passage of the air orother gas through said cable. At the joints in the cable or where the cable is repaired and' the continuity of the voids is in terrupted, I therefore, provide the by-pass tubes I5 15 which are Inserted into the metallic sheath of the cable to give continuity thereto and detachable connections 16.16'

for the insertion of the indicator 17. Flexible connections 17 are provided on the indi- 'cator 17 for effecting its connection in the by pass tubes 15, and unions 15 are provided 1n said b'y-pass tubes 15'to open said tubes for the insertion of the said indicator vl7. A

leak having been indicated by the registers 14, or by any other means, a high pressure been shut off. The leak is then found by the inspector as he passes along the length of the defective section of cable, the hissing noise of the escaping air through the leak enablin said leak to be locatedap roximatel an the exact spot tov be. then ibund by t e ins ector passing his hand along the cable in the vicinity. of tliehissing' noise,,the defective section of cablehaving been first determined by the indicator asdescribed below. For routine inspection, the indicator 17 which consists preferably of a short transparent tube having a light disk 20 therein is connected successively in the b -passes of successive joints, starting at'the st section of cable. If this section is sound the disk 20 will be driven towards the farther end of the tube, but if the leak be in that section, the disk will remain practically stationary for the reason that the air is escaping at some point before reaching the indicator tube 17. The same steps'are taken at the by-pass connections of the succeeding section, and so on until the leak, if any, be found. For convenience, if the joints are, too far a art, the l cables may be divided u into sma ler testing sections by openin t e metal sheathing at determined interva s and inserting 1nsulating compound to break the continuity of the a1r passages at these oints.

Having thus describe my invention, I

claim as new 1. In a system for locating leaks in dry core cables, the combination with aplurality of metal sheathed cables having voids for the passage of air or gas between the wires of the said cable, means for introducing air or gas under pressure into said voids of each cable, and means for indicating the Zuantity of air or gas passing into each of sai cables, of solid sectional air tight interruptions of said voids at intervals in said cables, by-pass tubes around said sectional interruptions, and an indicator to be inserted successively in each of said by-pass tubes, substantially as described and for the purpose set forth.

2. In a system of the class described, the combination with a plurality of dry core cables containing air or gas under pressure and having meters to indicate the quantity of air or gas passing into each of said cables; and by-pass tubes at the joints of said cables, of independent means for introducing higher pressure into any one cable, substantially as and for the purpose set forth.

In testimony whereof I have affiired my signature in presence of two Witnesses.

' p TROY COPE.

Witnesses:

C. LUDLOW LIVINGSTON, J As. L. CAMERON. 

